The present disclosure relates to a laser scanning unit that performs scanning with laser light radiated from a laser light source, and an image forming apparatus including the laser scanning unit.
Generally, in an image forming apparatus of electronic photograph type, laser light is radiated from a laser light source based on image data. The laser light is deflected by a polygon mirror (rotating polygon mirror), to scan the surface of a photosensitive drum. Thus, an electrostatic latent image is formed on the photosensitive drum. Here, in order to keep constant the density of a toner image obtained by developing the electrostatic latent image formed on the photosensitive drum, it is necessary to keep constant the intensity of the laser light from the laser light source.
Accordingly, the image forming apparatus may execute Automatic Power Control (APC) processing of detecting the intensity of the laser light radiated from the laser light source, and adjusting the intensity of the laser light radiated from the laser light source based on the detected intensity. However, if return light reflected from the polygon mirror enters a detector that detects the laser light radiated from the laser light source, the accuracy of the APC processing is reduced.
In order to prevent the influence of the return light, the image forming apparatus may include: a light dividing portion that divides the laser light radiated from the laser light source; and an optical detecting portion that detects the light amount of only one of the divided laser lights.